Plasma tryptophan tolerance curves in drug free normal controls, schizophrenic patients and prisoner volunteers

Abstract

Plasma TP was determined fluorometrically in four group of males: (1) normal controls (2) chronic schizophrenics (3) acute schizophrenics and (4) prison volunteers with personality disorders with and without symptoms of depression. To control for circadian rhythm all subjects were fasted overnight or in the afternoon and evening prior to withdrawal of venous blood. Fasting a.m. or p.m. plasma TP was within the range of normal for all groups. However, the acute schizophrenics and prison volunteers had lower plasma TP than the normal controls and chronic schizophrenics (p<middot;01. Plasma TP was determined before an 8:00 a.m. TP load and at , 1, 2, 4, and 7 hr after ingestion. A plasma tolerance curve was obtained with a peak at 1-2 hr which returned almost to normal at 7 hr. Various TP parameters were measured including fasting peak, maximal change in TP, time of peak, slope 2-4 and 4-7 hr, measured and normalized areas under the plasma tolerance curve, and plasma half-life. Almost no significant differences were found between normal controls and the chronic schizophrenics. Although all prison volunteers showed a markedly different TP tolerance curve from either the normal controls or chronic schizophrenics, depressed prisoners has a significantly lower and flatter curve. It appears that TP is well absorbed from the gastrointestinal tract and its plasma half-life is normal in chronic schizophrenics. Further studies in acute schizophrenics and depressed patients are indicated.